attrdict.py revision 5617:04b9d1e7ef2c 
1# Copyright (c) 2006 The Regents of The University of Michigan
2# All rights reserved.
3#
4# Redistribution and use in source and binary forms, with or without
5# modification, are permitted provided that the following conditions are
6# met: redistributions of source code must retain the above copyright
7# notice, this list of conditions and the following disclaimer;
8# redistributions in binary form must reproduce the above copyright
9# notice, this list of conditions and the following disclaimer in the
10# documentation and/or other materials provided with the distribution;
11# neither the name of the copyright holders nor the names of its
12# contributors may be used to endorse or promote products derived from
13# this software without specific prior written permission.
14#
15# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
18# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
19# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
21# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26#
27# Authors: Nathan Binkert
28
29__all__ = [ 'attrdict', 'multiattrdict', 'optiondict' ]
30
31class attrdict(dict):
32    """Wrap dict, so you can use attribute access to get/set elements"""
33    def __getattr__(self, attr):
34        if attr in self:
35            return self.__getitem__(attr)
36        return super(attrdict, self).__getattribute__(attr)
37
38    def __setattr__(self, attr, value):
39        if attr in dir(self) or attr.startswith('_'):
40            return super(attrdict, self).__setattr__(attr, value)
41        return self.__setitem__(attr, value)
42
43    def __delattr__(self, attr):
44        if attr in self:
45            return self.__delitem__(attr)
46        return super(attrdict, self).__delattr__(attr, value)
47
48class multiattrdict(attrdict):
49    """Wrap attrdict so that nested attribute accesses automatically create
50    nested dictionaries."""
51    def __getattr__(self, attr):
52        try:
53            return super(multiattrdict, self).__getattr__(attr)
54        except AttributeError:
55            d = optiondict()
56            setattr(self, attr, d)
57            return d
58
59class optiondict(attrdict):
60    """Modify attrdict so that a missing attribute just returns None"""
61    def __getattr__(self, attr):
62        try:
63            return super(optiondict, self).__getattr__(attr)
64        except AttributeError:
65            return None
66
67if __name__ == '__main__':
68    x = attrdict()
69    x.y = 1
70    x['z'] = 2
71    print x['y'], x.y
72    print x['z'], x.z
73    print dir(x)
74    print x
75
76    print
77
78    del x['y']
79    del x.z
80    print dir(x)
81    print(x)
82
83    x = multiattrdict()
84    x.y.z = 9
85    print x
86    print x.y
87    print x.y.z
88